Conventionally, a carbon--carbon combination has been used as a chief material for electric connection terminal members from the viewpoint of conductivity and corrosion resistance. The carbon--carbon combination is, however, expensive and involves a problem in formability, so it has been investigated to provide a combination of carbon and metal sheet. But, the carbon-metal sheet combination has a problem that an oxide or hydroxide is formed on the surface of a metal sheet combined with carbon and therefore the carbon-metal sheet combination has its conductivity remarkably decreased as i4 ages.
In order to solve the problem mentioned above, there has been an increasing demand for a material for making an electric connection terminal cheaper than carbon and as well conductive as carbon.
An electric connection terminal member made of metal-only material is cheap but poor in corrosion resistance because oxide or hydroxide is formed on the surface of such metal-made member as time passes, resulting in deterioration of conductivity. Therefore, the metal-only material is inadequate to use for the connection terminal member.
In order to solve the problem as mentioned above, it is a technical object to provide a surface-treated steel sheet having a low contact resistance excellent in conductivity, unchanged or stable conductivity even after aging, corrosion resistance, and adhesion, and also to provide a connection terminal member using this steel sheet.